The mission of the Mouse Genetics Laboratory shared resource, designated the Embryonic Stem Cell Technology Laboratory at the time of the original CCSG application, is to create genetically altered laboratory mice for investigations into the causes, development and treatment of human cancer by center members. This goal is being met by a full time staff of technical experts in mouse embryo manipulations including but not limited to pronuclear injection, blastocyst injection, embryo/sperm cyropreservation, and embryonic stem cell culture.